Random fun facts that are actually true

🐙 Fun facts about animals

• Octopuses have three hearts and blue blood.Source: Smithsonian Ocean
• A group of flamingos is called a flamboyance.Source: Oxford English Dictionary usage
• Wombats produce cube-shaped poop, thanks to the way their intestines stretch.Source: Soft Matter, 2021
• Sea otters often hold hands while they sleep so they don't drift apart.Source: Monterey Bay Aquarium
• A shrimp's heart is in its head.Source: Marine biology texts
• Butterflies taste with sensors on their feet.Source: Natural History Museum, London
• Giraffes have seven neck bones, the same number as humans. Each one is just much longer.Source: Smithsonian's National Zoo
• A blue whale's heart weighs about 180 kg (400 lb).Source: Stanford, 2019 heart-rate study
• Penguins have knees. They are hidden inside their feathers.Source: Natural History Museum, London
• Starfish have no brain and no blood.Source: NOAA Ocean Service
• Crows can recognise individual human faces and remember people who treated them badly for years.Source: University of Washington, 2010
• Axolotls can regrow lost legs, parts of their heart and even parts of their brain.Source: Nature, 2018
• Owls can't move their eyes, so they turn their heads, up to about 270 degrees.Source: Johns Hopkins Medicine, 2013
• Polar bears have black skin under their fur, and the fur itself is transparent, not white.Source: Polar Bears International
• Honeybees tell each other where the flowers are with a "waggle dance".Source: Karl von Frisch, Nobel Prize 1973
• Koalas have fingerprints so close to ours that they are hard to tell apart under a microscope.Source: Nature, 1996
• Hummingbirds can fly backwards.Source: Smithsonian's National Zoo
• Cats can't taste sweetness. They lack the gene for the sweet taste receptor.Source: PLOS Genetics, 2005
• A snail has thousands of tiny teeth on its tongue.Source: Natural History Museum, London
• Elephants can "hear" through their feet, picking up rumbles in the ground from far away.Source: Stanford, Caitlin O'Connell-Rodwell

🪐 Fun facts about space

• A day on Venus (243 Earth days) is longer than a year on Venus (225 Earth days).Source: NASA
• Saturn is less dense than water. In a big enough bathtub, it would float.Source: NASA
• Footprints left on the Moon could last millions of years, because there is no wind to blow them away.Source: NASA
• Sunlight takes about 8 minutes and 20 seconds to reach Earth.Source: NASA
• About 1.3 million Earths would fit inside the Sun.Source: NASA
• Jupiter's Great Red Spot is a storm wider than Earth that has raged for hundreds of years.Source: NASA
• Space is silent. Sound needs air or another material to travel through.Source: NASA
• Olympus Mons on Mars is about 22 km high, two and a half times the height of Mount Everest.Source: NASA
• The International Space Station circles Earth about every 90 minutes, so astronauts see around 16 sunrises a day.Source: NASA
• Uranus spins on its side, probably knocked over by a giant collision long ago.Source: NASA
• The Moon drifts about 3.8 cm (1.5 in) further from Earth every year.Source: NASA, lunar laser ranging
• Astronauts grow up to about 5 cm (2 in) taller in space, because their spines stretch without gravity.Source: NASA
• A year on Mercury lasts just 88 Earth days.Source: NASA
• Venus is the hottest planet, even though Mercury is closer to the Sun. Its thick clouds trap the heat.Source: NASA
• Pluto is narrower than the United States is wide.Source: NASA (Pluto is about 2,380 km across)
• A teaspoon of neutron star material would weigh around a billion tonnes on Earth.Source: NASA
• Mars has blue sunsets.Source: NASA, Curiosity rover images
• There is a planet-sized cloud of water vapour around a black hole 12 billion light years away, with 140 trillion times the water in Earth's oceans.Source: NASA / Caltech, 2011
• The Sun makes up about 99.8% of all the mass in our solar system.Source: NASA

🫀 Fun facts about the human body

• Babies are born with about 300 bones. Many fuse together, leaving adults with 206.Source: Cleveland Clinic
• The smallest bone in your body is the stapes, in your ear. It is about the size of a grain of rice.Source: Cleveland Clinic
• You can't hum while holding your nose closed. Try it.Source: Basic physiology: humming needs air out through the nose
• Fingernails grow faster than toenails.Source: American Academy of Dermatology
• Your heart beats about 100,000 times a day.Source: American Heart Association
• Your brain is about 2% of your body weight but uses about 20% of its energy.Source: Scientific American
• Stretched out, the DNA in one of your cells would be about 2 metres long.Source: National Human Genome Research Institute
• You are about 1 cm taller in the morning than at night. Your spine squashes a little during the day.Source: Cleveland Clinic
• Tooth enamel is the hardest substance in the human body, but it cannot grow back.Source: American Dental Association
• About 8% of human DNA comes from ancient viruses that infected our ancestors.Source: Nature, 2016
• Your small intestine is about 6 metres (20 ft) long.Source: Cleveland Clinic
• Goosebumps are a leftover from furry ancestors: they made fur stand up for warmth or to look bigger.Source: Harvard, 2020
• Humans glow faintly in the dark, but the light is about 1,000 times too weak for our eyes to see.Source: PLOS ONE, 2009
• The cells lining your stomach are replaced every few days, so the acid doesn't digest you.Source: Cell biology texts
• Your nose and sinuses make about a litre of mucus a day. Most of it you swallow.Source: Cleveland Clinic
• Your eyes blink about 15 to 20 times a minute, more than 10,000 times a day.Source: American Academy of Ophthalmology
• Your body has about as many bacteria as human cells.Source: Cell, 2016 (Sender, Fuchs and Milo)
• Your left and right lungs are different sizes. The left one is smaller to make room for your heart.Source: Cleveland Clinic
• Adult humans have around 600 muscles.Source: Cleveland Clinic

🏛️ Fun history facts

• Cleopatra lived closer in time to the Moon landing than to the building of the Great Pyramid.Source: Pyramid c. 2560 BC, Cleopatra died 30 BC, Moon landing 1969
• Oxford University was already teaching students before the Aztec capital Tenochtitlan was founded.Source: Oxford from 1096, Tenochtitlan 1325
• The shortest war in history, between Britain and Zanzibar in 1896, lasted less than 45 minutes.Source: Guinness World Records
• Napoleon was about 1.69 m (5 ft 7 in), average for his time. The "short" myth came partly from French inches being longer.Source: Encyclopaedia Britannica
• The Great Pyramid of Giza was the tallest human-made structure on Earth for about 3,800 years.Source: Encyclopaedia Britannica
• Vikings almost certainly didn't wear horned helmets. That look came from 1800s costume designers.Source: National Museum of Denmark
• Woolly mammoths still lived on Wrangel Island when the Egyptian pyramids were being built.Source: Mammoths survived there until about 4,000 years ago
• The fax machine (1843) was invented before the telephone (1876).Source: Alexander Bain's patent, 1843
• Nintendo was founded in 1889, as a company making playing cards.Source: Nintendo
• Ketchup was sold as a medicine in the United States in the 1830s.Source: Smithsonian Magazine
• The Hundred Years' War actually lasted 116 years (1337 to 1453).Source: Encyclopaedia Britannica
• In 1919, a flood of molasses swept through Boston at about 50 km/h.Source: The Great Molasses Flood, Boston
• Abraham Lincoln is in the US National Wrestling Hall of Fame. He lost only one recorded match.Source: National Wrestling Hall of Fame
• When countries switched to the Gregorian calendar in 1582, 4 October was followed by 15 October.Source: Papal bull Inter gravissimas
• The first photo of a person was taken by accident in 1838: a man having his boots polished on a Paris street.Source: Louis Daguerre, Boulevard du Temple
• The University of al-Qarawiyyin in Fez, Morocco, founded in 859, is often called the oldest university still running.Source: UNESCO, Guinness World Records
• The Eiffel Tower grows about 15 cm taller in summer, because the iron expands in the heat.Source: Société d'exploitation de la tour Eiffel
• The first recorded Olympic Games were held in 776 BC, with a single running race.Source: International Olympic Committee
• The ancient Romans had a goddess of sewers, Cloacina.Source: Roman religion texts

🍌 Fun food facts

• Botanically, bananas are berries, but strawberries are not.Source: Botany: a berry develops from one flower with one ovary
• Peanuts aren't nuts. They are legumes, like peas and beans.Source: USDA
• Sealed honey can last for thousands of years. Pots of it have been found in ancient Egyptian tombs.Source: Smithsonian Magazine
• Apples float in water because about a quarter of an apple is air.Source: Food science texts
• A pineapple takes about 18 to 24 months to grow.Source: University of Hawaiʻi
• Cashews grow on the outside of a fruit called the cashew apple.Source: Food and Agriculture Organization
• Early cultivated carrots were purple or yellow. Orange carrots became common after Dutch growers bred them in the 1600s.Source: World Carrot Museum
• White chocolate contains no cocoa solids, only cocoa butter, sugar and milk.Source: US FDA standard of identity
• In colonial America, lobster was cheap food, given to servants and prisoners.Source: Smithsonian Magazine
• A single piece of spaghetti is called a spaghetto.Source: Italian grammar
• Ripe cranberries bounce. Farmers have used bounce tests to sort them.Source: Ocean Spray / cranberry growers
• Most "wasabi" served outside Japan is horseradish and mustard dyed green.Source: Smithsonian Magazine
• The potato was the first vegetable grown in space, in 1995.Source: NASA and University of Wisconsin
• Birds can't feel the heat of chilli peppers, so they happily eat them and spread the seeds.Source: Tewksbury and Nabhan, Nature, 2001
• Cucumbers are about 95% water.Source: USDA
• A strawberry has about 200 seeds on the outside.Source: California Strawberry Commission
• Chocolate is poisonous to dogs because of a chemical called theobromine.Source: American Kennel Club
• Avocados don't ripen on the tree. They only start softening after being picked.Source: California Avocado Commission
• Ketchup leaves a glass bottle fastest if you tap on the "57" on the neck, not the bottom.Source: Heinz

⚡ Fun science facts

• Lightning can reach about 30,000 °C, around five times hotter than the surface of the Sun.Source: US National Weather Service
• Australia is wider than the Moon. Australia is about 4,000 km across, the Moon about 3,475 km.Source: Geoscience Australia, NASA
• Antarctica is the largest desert in the world. A desert is defined by low rain or snow, not heat.Source: National Geographic
• Sound travels about four times faster in water than in air.Source: NOAA
• Diamonds and pencil graphite are both made of pure carbon. Only the arrangement of the atoms differs.Source: Royal Society of Chemistry
• Russia spans 11 time zones.Source: Time and Date
• Canada has more lakes than the rest of the world combined.Source: Natural Resources Canada
• The Sahara was green, with lakes and hippos, between about 11,000 and 5,000 years ago.Source: Nature Communications
• Only about 3% of the water on Earth is fresh water, and most of that is frozen.Source: US Geological Survey
• Old church windows are thicker at the bottom because of how glass was made, not because glass flows.Source: American Journal of Physics, 1998
• The shore of the Dead Sea is the lowest dry land on Earth, more than 430 m below sea level.Source: Encyclopaedia Britannica
• Earth is not a perfect ball. It bulges at the equator, about 43 km wider than it is tall.Source: NOAA
• Water can boil and freeze at the same time, at the "triple point" of low pressure and 0.01 °C.Source: National Institute of Standards and Technology
• Liquid oxygen is pale blue.Source: Royal Society of Chemistry
• A cloud can weigh more than 500 tonnes, about as much as 100 elephants.Source: US Geological Survey
• Bananas are slightly radioactive, because they contain potassium-40.Source: US Nuclear Regulatory Commission
• Hot water freezing faster than cold, the "Mpemba effect", is still argued about by physicists.Source: Nature, Scientific Reports, 2016
• Africa has 54 countries recognised by the United Nations.Source: United Nations
• Earth's days are getting longer by about 1.7 thousandths of a second every century.Source: Proceedings of the Royal Society A, 2016

About our facts

Are these fun facts true?

Yes. Every fact has a source, mostly NASA, museums, universities and peer-reviewed studies. We skip popular "facts" that turn out to be myths, and put those in our fact or myth quiz instead.

Can I use these facts in a quiz or class?

Yes, they're free to use. A link back is appreciated.

What is the most surprising fun fact?

Our favourite: Cleopatra lived closer in time to the Moon landing than to the building of the Great Pyramid.